Method for production of alkaryl sulfonate detergent compositions



Jan. 14, 1958 F. M. SMITH METHOD FOR PRODUCTION OF ALKARYL SULFONATE DETERGENT COMPOSITIONS Filed Nov. 25, 1949 INVENTOR.

F. M SMITH mzw A TTORNE VS METHOD FOR PRODUCTION OF ALKARYL SUL- F ONATE DETERGENT COMPOSITIONS Fredrick M. Smith, Bartlesville, Okla, assignor to Phillips Petroleum Company, a corporation of Delaware Application November 25, 1949, Serial No. 129,476

8 Claims. (Cl. 252-161) This invention relates to a novel detergent composition comprising a mixture of long-chain and short-chain alkyl aromatic sulfonates and to a process for producing such a detergent composition. In another of its aspects, this invention relates to a process for sulfonating alkaryl hydrocarbons to produce detergents. In still another of its aspects, this invention relates to a process for producing oil-free detergents.

In the manufacture of detergent materials from alkaryl hydrocarbons, a process commonly employed by the prior art involves sulfonation of the hydrocarbon with a large excess of concentrated sulfuric acid or of oleum, neutralization of the resultant mixture with sodium hydroxide and evaporation to remove water. The product thus obtained will contain considerable amounts of sodium sulfate which acts as a so-called builder to enhance its detergent properties. In many instances, additional amounts of sodium sulfate are added to further improve the product although other inorganic salts such as phosphates, pyrophosphates, various polyphosphates, and the like are also employed as additives to or replacements for the sodium sulfate provided by the neutralization of the acid. A typical detergent prepared in this manner will comprise about 30 to 40 percent alkaryl sulfonate and from 60 to 70 percent sodium sulfate and/or other inorganic builders.

The purpose of employing such a large excess of concentrated sulfuric acid or of oleum in the sulfonation procedures of the prior art is to sulfonate as much of the alkaryl hydrocarbon as is possible, since the presence of even very small amounts, say as little as 0.75 percent, of unsulfonated hydrocarbon exerts a deleterious effect on the detergent properties of the product. However, even with a large excess of sulfonating agent, from three to ten percent of the hydrocarbon will ordinarily remain unsulfonated. A portion of the unsulfonated hydrocarbon will be removed by steam distillation during the evaporation step following the sulfonation step but, even so, there is usually from about one to as much as five percent of unsulfonated hydrocarbon residue in the product. In general, for any particular alkylaromatic mixture, the factors governing the quantity of unsulfonated residues will include the severity of the sulfonation and the volatility of the hydrocarbon. Obviously any unsulfonatable constituents, such as parafiins and naphthenes, will likewise contribute to these amounts. These residues will boil at approximately the temperature level of the alkaryl hydrocarbon used and hence are not readily separable by ordinary fractional distillation.

Still further in the prior art, it has been found necessary to employ a specific detergent having a certain chemical structure in a specific application. Thus it is known that sulfonates of alkyl aromatics having from 12 to 16 carbon atoms in the substituent alkyl group are especially fitted for use as a detergent in hard waters but are not suitably efiicient in soft waters. Other detergents are suitable for soft waters but not for hard water. Obviously, a detergent which possesses properties which permit it 526,015 Patented Jan. 14, 1958 to be employed interchangeably in either hard or soft waters would be highly desirable.

It has now been found that a mixture of a sulfonate oi. a long-chain alkyl aromatic hydrocarbon and a sulfonate of a short-chain alkyl aromatic hydrocarbon possesses detergent properties which permit its use as a detergent in either hard or soft water.

It has also been found that excess sulfonating agent which is employed to sulfonate a long-chain alkyl aromatic hydrocarbon can be further employed to sulfonate a shortchain alkyl aromatic hydrocarbon to thereby produce the novel composition of this invention. It has been found further that unsulfonated higher boiling hydrocarbons commonly present in the effluent from an alkaryl hydrocarbon sulfonation zone can be eliminated therefrom by extraction with a short-chain alkyl aromatic hydrocarbon. Thus, the short-chain alkyl aromatic hydrocarbon of this invention concomitantly serves two purposes i. e. a portion of it is sulfonated by excess sulfonating agent to produce the novel detergent composition of this invention while the remaining portion extracts the unsulfonated higher boiling hydrocarbons from the sulfonated product.

Thus, according to this invention, there is provided a novel detergent composition comprising an admixture of a sulfonate of a long-chain alkyl aromatic hydrocarbon and a sulfonate of a short-chain alkyl aromatic hydrocarbon which composition exhibits superior properties permitting its use in either hard or soft water. Still according to this invention, there is provided a process for producing the detergent composition of this invention which comprises sulfonating a long-chain alkyl aromatic hydrocarbon with an excess of a sulfonating agent in a first sulfonation zone, then admixing a short-chain alkyl aromatic hydrocarbon with the resulting effluent from said zone, sulfonating at least a portion of said short-chain alkyl aromatic hydrocarbon with the excess of said sulfonating agent and recovering a mixture of sulfonated longand short-chain alkyl aromatic hydrocarbons. Still further according to this invention, there is provided a process for producing a mixture of sulfonated longand shortchain alkyl aromatic hydrocarbons free from unsulfonated hydrocarbon which comprises sulfonating a long-chain alkyl aromatic hydrocarbon with an excess of sulfonating agent in a first sulfonation zone, admixing a short-chain alkyl aromatic hydrocarbon with the effluent from said first zone, sulfonating at least a portion of said shortchain alkyl aromatic hydrocarbon with the excess of said sulfonating agent in a second sulfonation zone, separating unsulfonated short-chain alkyl aromatic hydrocarbon from the effluent of said second zone to thereby extract unsulfonated higher boiling hydrocarbons from the sulfonated effluent from said second zone and recovering a detergent product from said efiluent from said second zone.

In order to more fully set forth the process of this invention, a specific embodiment will be described with particular reference to the attached diagrammatic drawmg.

Referring to the drawing, a long-chain alkyl aromatic hydrocarbon is introduced via line 1 into sulfonating zone 2 where it is agitated with an excess of sulfonating agent introduced from line 3. From the sulfonating zone 2, the mixture is conveyed via line 4 to second sulfonating zone 5 where it is admixed with a short-chain alkyl aromatic hydrocarbon introduced via line 6. After agitation and further reaction, the sulfonated mixture is discharged via line 7 to separator 8 where it is separated by gravity into a hydrocarbon phase and a sulfonic-sulfuric acid phase. The heavier acid phase is removed via line 9 to neutralizing chamber 10 where it is treated with a 30 to 50 weight percent aqueous solution of sodium hydroxide introduced via line 11, thereby converting the sulfonic and sulfuric acids to the corresponding sodium sulfonates and sulfates. The slurry from the neutralizer is then discharged via line 12 to dryers (not shown) where water is removed to provide the detergent material of my invention, comprising a mixture of long chain and short-chain alkyl aromatic sulfonates. The hydrocarbon phase from separator 8, comprising a solution of high boiling unsuifonated hydrocarbon residues from the first sulfonation zone in lower boiling hydrocarbon residues from the second sulfonation zone, is conveyed via line 13 to fractionator 14. There, the low boiling hydrocarbon, now partially depleted in aromatic content, is removed overhead through line 15 and the higher boiling hydrocarbon remaining in the kettle of the fractionator is removed via line 16. At least a portion of the low boiling aromaticcontaining hydrocarbon is recycled to the second sulfonation zone through lines 17 and 6, the remainder being discharged from the system via line 18. In a similar manner, all or a portion of the high boiling hydrocarbon is recycled to the first sulfonation zone 2 via lines 16, 19, and 1 the remainder, if any, is discharged through line 20. In some instances, it is desirable to introduce a separating system 21 in line 9 wherein the acid phase from separator 8 is mixed with water from line 22 in an amount sufiicient to dilute the said acid phase by from to 35 volume percent. Such dilution will reduce the solvent power of the acid mixture for hydrocarbon to a minimum. By so operating, any residual hydrocarbon retained in solution in the acid mixture will be reduced to an insignificant quantity by dissolubilization and will rise to the surface where it can be removed via line 23.

The long-chain alkyl aromatic hydrocarbon used as the primary sulfonating stock can be an alkylated benzene or an alkylated benzene homologue in which the substituent alkyl group contains an average of from 10 to carbon atoms. Included within the benzene homologues mentioned above are toluene, xylene, ethylbenzene, etc. Alternatively, it is advantageous to employ a mixture of various long-chain alkyl aromatic hydrocarbons derived from a hydrocarbon fractionating zone and, in such case, the aromatic fraction should boil within the range of approximately 525 to 700 F. Such a fraction need not comprise solely aromatic hydrocarbons but can also contain other hydrocarbons boiling within that range such as parafiinic, naphthenic, etc., hydrocarbons. The shortchain alkyl aromatic hydrocarbon can be an alkyl aromatic in which the average total number of carbon atoms in the substituent alkyl group is from four to eight, preferably from six to eight. The aromatic nucleus can be of the same general type as that of the long-chain aromatic hydrocarbon described above. It has been found advantageous to employ a deolefinized cracked naphtha fraction boiling in the range 350 to 475 F. as a source of feedstock for the second sulfonation zone. Such naphtha fractions usually contain from ten to forty percent aromatic constituents which are suitable for the process of this invention. The amount of short-chain alkyl aromatic hydrocarbon to be employed can be from about two to ten, preferably from about three to six, pounds per pound of sulfonation elhuent from the first sulfona-tion zone. The exact amount of the short-chain alkyl aromatic hydrocarbon employed will depend upon its purity, the amount of its sulfonate desired in the final product, the amount of excess sulfonating agent available from the first sulfonation zone, etc. However, it is usually preferable to employ an excess of the short-chain alkyl aromatic hydrocarbon in order to ensure that sufiicient of it will be present in an unsulfonated condition for the purpose of extracting the unsulfonated higher boiling hydrocarbons from the sulfonated product. In such cases, the proportion of the short-chain alkyl aromatic hydrocarbon which is sulfonated can be regulated by adjusting the temperature and reaction time in the second sulfonaion. z ne- The sulfonating temperature maintained in the first sultonating zone is preferably lower than the temperature of the second sulfonating zone. Thus, the temperature of the first zone can be within the range of about 40 to 120 F, preferably about 55 to 100 F. The temperature of the second sulfonating zone should be within the range of about 900 to 200 F., preferably about 100 to 175 F.

In the first sulfonation zone, the amount of concentrated sulfuric acid or of oleum employed is from one to three parts by weight per part by weight of aromatic hydrocarbon feed. This sulfonating acid can be to percent sulfuric acid or can be oleum containing from 10 to 35 percent sulfur trioxide. The excess of acid from this zone will have sufficient residual strength to sulfonatc at least a portion, that is, from 10 to 60 percent, preferably from 15 to 40 percent, of the aromatic constituents of the aromatic-containing hydrocarbon fed to the second sulfonation zone.

The proportion of short-chain alkyl aromatic sulfonate in the detergent composition of this invention is a function of the excess of sulfonating acid used in the first sulfonation zone, the residence time in the second sulfona tion zone, and the concentration of aromatic constituents in the lower boiling aromatic-containing hydrocarbon supplied to the said second sulfonation zone. regulation of these factors, the proportion of lower molecular weight sulfonate in the final product can be varied from about 10 to about 50 percent of the total detergent weight as desired. Ordinarily it is preferable to employ from 15 to 30 weight percent of the lower molecular weight detergent in the final product.

Suitable builders, when such are desired, can be added,

to the sulfonate stream either in the neutralizer or at any period thereafter prior to drying. These builders can comprise additional sodium sulfate or can be phosphates, pyrophosphates, polyphosphates, or other additives which provide specialized properties in the final detergent product.

EXAMPLE I A run was made according to the process described, using an alkyl toluene boiling in the range 550 to 650 F. and having an average of about 12 carbon atoms in the alkyl group as the primary aromatic feed stock. This hydrocarbon was sulfonated by treatment with 50 percent excess by weight of 20 percent oleum at a temperature of 60 F. for 30 minutes. The sulfonation mixture was then commingled with four times its weight of a deolefinized cracked naphtha fraction boiling in the range of 350 to 450 F. and containing 16 percent alkyl aro-. matic hydrocarbons having an average of about six car.- bon atoms in the alkyl group. The mixture was agitated for 20 minutes at a temperature of 100 F. after which it was separated by gravity into an acid phase and a hydrocarbon phase. The acid phase was removed and neutralized with 30 percent aqueous sodium hydroxide. The resulting sulfonate and sulfate were then dried. The

hydrocarbon phase was fractionated and the overhead of less than 0.25 percent and was therefore regarded as oil-free.

EXAMPLE II A portion of the above-described detergent material, heremafter referred to as detergent A, was tested by standard washing tests carried out in a Launderometer in comparison with four other detergent materials having the following compositions;

By suitable ."Detergent B comprised about percent long-chain alkyl aromatic sulfonate having an average of 12 carbon atoms in the alkyl group, percent sodium sulfate, and 0.6 percent unsulfonated oil, a commercially available synthetic detergent, included here for comparative puroses.

p Detergent C was an oil-free material comprising 40 percent long-chain alkyl aromatic sulfonate having an average of 12 carbon atoms in the alkyl group, 30 percent short-chain alkyl aromatic sulfonate having an average of six carbon atoms in the alkyl group and 30 percent sodium sulfate.

Detergent D was similar to detergent C except that it contained 30 percent long-chain alkyl aromatic sulfonate, 30 percent short-chain alkyl aromatic sulfonate, and 40 percent sodium sulfate.

Detergent E was also an oil-free material comprising 40 percent long-chain alkyl aromatic sulfonate, 30 percent sodium p-toluene sulfonate, and 30 percent sodium sulfate.

The washing tests were carried out by washing samples of .soiled cotton cloth in distilled water and in water of 350 p. p. m. of calcium carbonate hardness, using varying amounts of detergent in each. The efiiciency of each detergent was determined by the percent reflectance re,- stored by the washing. The results of these tests are tabulated below.

Detergents A, C and D, which embody the advantages of the present invention, show marked superiority over detergent B, which is an ordinary detergent, in both hard and soft water. Tests on detergent E indicate that lower washing efficiency is obtained when the short-chain alkyl aromatic sulfonate constituent is prepared from an alkyl aromatic having an insufficient number of carbon atoms in the alkyl group.

The introduction of the lower boiling, short-chain alkyl aromatic-containing hydrocarbon material into the second sulfonation zone is advantageous from several viewpoints. A portion of the aromatic constituents of this material is sulfonated by the excess acid remaining from the first sulfonation zone, thus utilizing the acid to the greatest possible extent by producing a sulfonate of an alkaryl hydrocarbon having a shorter alkyl chain than that produced in the first sulfonation zone. Also, this short-chain alkyl aromatic sulfonate contributes markedly to the detergent properties of the final product. Furthermore, high boiling unsulfonated hydrocarbon from the first sulfonation zone is extracted by the.excess of the lower boiling, short-chain alkyl aromatic-containing hydrocarbon in the second sulfonation zone and removed therewith in the subsequent separation and removal of the hydrocarbon phase from the acid phase. Thus, a substantially oil-free detergent product is obtained since any residual unsulfonated low boiling hydrocarbon remaining dispersed in the acid phase is substantially completely removed by steam distillation in the driers. A still further advantage of the invention lies in the recovery of the high boiling unsulfonated hydrocarbon material for recycling to the first sulfonation zone, thereby efliciently utilizing a material which has heretofore been an objectionable and deleterious contaminant in the production of detergents of this type.

Reasonable variation and modification are possible admixture of a sulfonate of a high molecular weight alkaryl hydrocarbon and a sulfonate of a low molecular weight alkaryl hydrocarbon which admixture has superior detergent powers in both soft and hard waters and further that such compositions can be prepared by sulfonating ahigh molecular weight alkaryl hydrocarbon with an excess of sulfonating agent in a first zone and then reacting at least a portion of the excess sulfonating agent with an added excess of low molecular weight alkaryl hydrocarbon which serves not only as a reactant for producing the sulfonate thereof for the final detergent composition, but also serves to extract unsulfonated high molecular weight hydrocarbons from the final product to produce an oil-free detergent composition.

I claim:

1. A process for producing an oil-free detergent composition comprising sulfonating a long-chain alkyl mononuclear aromatic hydrocarbon having from ten to fifteen carbon atoms in its alkyl group with one to three times its weight of concentrated sulfuric acid in a first sulfonating zone at a temperature between 40 and F., admixing from two to ten weights of a short-chain alkyl mononuclear aromatic hydrocarbon having from four to eight carbon atoms in its alkyl group with each weight of the total efiluent from said first zone, passing the resulting admixture to a second sulfonating zone and sulfonating in said second zone between 10 and 60 percent of said short-chain alkyl aromatic hydrocarbon with the excess of sulfuric acid contained in said efiiuent, separating the unsulfonated short-chain alkyl aromatic hydrocarbon from the sulfonated product to thereby concomitantly extract therewith unsulfonated higher boiling hydrocarbons from the said sulfonated product, and recovering the sulfonated product.

2. The process of claim 1 wherein the aromatic nucleus of said long-chain and said short-chain alkyl aromatic hydrocarbons is a phenyl radical.

3. The process of claim 1 wherein the long-chain alkyl aromatic hydrocarbon is a long-chain alkyl toluene and the short-chain alkyl aromatic hydrocarbon is contained in a deolefinized cracked naphtha fraction boiling in the range of 350 to 450 F. which fraction is added to said second zone.

4. A process for producing an oil-free detergent composition comprising sulfonating therein a long-chain alkyl mononuclear aromatic hydrocarbon having from ten to fifteen carbon atoms in its alkyl group with an excess of sulfonating agent in a first sulfonating zone, admixing a short-chain alkyl mononuclear aromatic hydrocarbon having from four to eight carbon atoms in its alkyl group with the effluent from said first zone, passing the resulting admixture to a second sulfonating zone and sulfonating therein said short-chain alkyl aromatic hydrocarbon with the excess of said sulfonating agent contained in said effiuent, separating the unsulfonated short-chain alkyl aromatic hydrocarbon from the sulfonated product to thereby concomitantly extract any unsulfonated higher boiling hydrocarbons from the said sulfonated product, and recovering the sulfonated product.

5. The process of claim 4 wherein the said sulfonating agent is oleum.

6. A process for producing an oil-free detergent composition comprising sulfonating a long-chain alkyl mononuclear aromatic hydrocarbon with one to three times its weight of a sulfonating agent in a first sulfonating zone at a temperature between 40 and 120 F., admixing from two to ten weights of a short-chain alkyl mononuclear aromatic hydrocarbon with each weight of the total efiluent from said first zone, passing the resulting admixture to a second sulfonating zone and sulfonating in said second zone between 10 and 60 percent of said short-chain alkyl aromatic hydrocarbon with the excess of said sulfonating agent containedin said efiiuent, separating the unsulfonated short-chain alkyl aromatic hydrocarbon from the sulfonated product to thereby concomitantly extract therewith unsulfonated higher boiling hydrocarbons from the said sulfonated product, and recovering the sulfonated product.

7. A process for producing an oil-free detergent composition comprising sulfonating a long-chain alkyl mononuclear aromatic hydrocarbon having from ten to fifteen carbon atoms in its alkyl group with an excess of a sulfonating agent in a first sulfonating zone, admixing substantial quantities of a short-chain alkyl mononuclear aromatic hydrocarbon having from four to eight carbon atoms in its alkyl group with the efliuent from said first zone, passing the resulting admixture to a second sulfonating zone and sulfonating in said second zone between 10 and 60 percent of said short-chain alkyl aromatic hydrocarbon with the excess of said sulfonating agent contained in said efiluent, separating the unsulfonated shortmixing from't-wo to ten weights of a short-chain alkyl mononuclear aromatic hydrocarbon having from four to' eight carbon atoms in its alkyl group with each weight of the totalefiiuent from said first zone, passing the resulting admixture to a second sulfonating zone and sulfonating in said second zone between 10 and 60 percent of said short-chain alkyl aromatic hydrocarbon with the excess sulfuric acid in said efiluent, separating the effluent from said second zone into an acid phase and a hydrocarbon phase, diluting said acid phase with water thereby dissolubilizing any hydrocarbons contained in said acid phase, passing the resulting dilute acid phase to a neutralizer, neutralizing said acid phase with sodium hydroxide .to form the desired sodium salts of said longchain and short-chain alkyl aromatic sulfonates, and recovering the sodium salts of said sulfonates.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Perry-Schwartz: Surface Active Agents, page 1!? (1949), Interscience Publishers, Inc.

Cook Oct. 18, 1938 

1. A PROCESS FOR PRODUCING AN OIL-FREE DETERGENT COMPOSITION COMPRISING SULFONATING A LONG-CHAIN ALKYL MONONUCLEAR AROMATIC HYDROCARBON HAVING FROM TEN TO FIFTEEN CARBON ATOMS IN ITS ALKYL GROUP WITH ONE TO THREE TIMES ITS WEIGHT OF CONCENTRATED SULFURIC ACID IN A FIRST SULFONATING ZONE AT A TEMPERATURE BETWEEN 40* AND 120*F. ADMIXING FROM TWO TO TEN WEIGHTS OF A SHORT-CHAIN ALKYL MONONUCLEAR AROMATIC HYDROCARBON HAVING FROM FOUR TO EIGHT CARBON ATOMS IN ITS ALKYL GROUP WITH EACH WEIGHT OF THE TOTAL EFFLUENT FROM SAID FIRST ZONE, PASSING THE RESULTING ADMIXTURE TO A SECOND SULFONATING ZONE AND SULFONATING IN SAID SECOND ZONE BETWEEN 10 AND 60 PECENT OF SAID SHORT-CHAIN ALKYL AROMATIC HYDROCARBON WITH THE EXCESS OF SULFURIC ACID CONTAINED IN SAID EFFLUENT, SEPARATING THE UNSULFONATED SHORT-CHAIN ALKYL AROMATIC HYDROCARBON FROM THE SULFONATED PRODUCT TO THEREBY CONCOMITANTLY EXTRACT THEREWITH UNSULFONATED HIGHER BOILING HYDROCARBONS FROM THE SAID SULFONATED PRODUCT, AND RECOVERING THE SULFONATED PRODUCT. 